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Features of Cast Iron Smelting in Induction Crucible Furnaces

Grachev V.

Archives of Foundry Engineering

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2017

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Vol. 17, iss. 3

45--50

EN

The article describes the trend towards increased use of induction crucible furnaces for cast iron smelting. The use of gas cupola’s duplex process – induction crucible furnace – has been proved the effective direction of scientific and technical advance in the foundry industry. Gas cupolas and induction furnaces are used for cast iron smelting at the Penza Compressor Plant where in the 1960s the author developed and introduced gas cupolas for the first time in the world. In the article, the author represents the findings of the investigation on thermodynamics of crucible reduction of silicon, which is pivotal when choosing the technological mode for cast iron smelting in induction furnaces. The author proposes a new reaction crucible diagram with due account of both partial pressure and activity of the components involved into the process. For the first time ever, the electrochemical mechanism of a crucible reaction has been studied and the correctness of the proposed diagram has been confirmed.

2

Influence of addition of briquettes with dust content into the charge of electric induction furnace on cast iron quality

Pribulová A., Futáš P., Baricová D.

Archives of Foundry Engineering

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2012

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Vol. 12, iss. 3

95-98

EN

Foundry dust from blasting and grinding of castings contain a high amount of iron, ergo it is possible its recycling in foundry process. Dust was compacted by briquetting, two kinds of briquettes were prepared (A contained 95% magnetic part of dust from casting blasting +5% bentonite and B contained 95% mixture of dust from casting grinding and magnetic part of dust from casting blasting + 5% bentonite) and used as a part of charge into the electric induction furnace. It was found that addition of briquettes has had an influence of a chemical composition of cast iron above all on content of sulphur, phosphorus and silicon. It was not reflected in decrease in tensile strength and in microstructure. Yield of metal from briquettes was not lower then 70%.

3

The technology of recovery melting of steel for turbine castings in induction furnace

Mańkowski P., Kalandyk B., Zapała R.

Archives of Foundry Engineering

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2010

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Vol. 10, iss. 4

137--140

EN

A technology of recovery melting of G17CrMo 5-5 and G17CrMoV 5-10 steel for turbine castings in induction furnace followed by ladle-furnace refining (EIF+LF) was evaluated. Studies included testing of molten steel metallurgical purity, mechanical tests and evaluation of benefits for both economy and ecology resulting from the introduction of new technology. It was concluded that using the EIF+LF technology for production of massive castings of large overall dimensions (26Mg) has brought numerous multi-level advantages.

4

Possibilities of pelletizing and briquetting of dusts from castings grinding

Pribulova A., Baricova D., Futas P., Gengel P.

Archives of Foundry Engineering

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2010

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Vol. 10, iss. 2 spec.

123--126

EN

Foundry dust can be divided into three groups: metallic dust with Fe content over 70%, mixed dust with Fe or SiO2 content between 10–70% and sand wastes with minimum content of SiO2 about 70%. Dust from castings grinding with high Fe content (87.9%) is still landfill in Slovakia. The aim of experiments with dust from grinding has been to find the cheapest way of dust agglomeration with minimum amount of binder because of melting in the electric induction furnace. The dust was pelletized and briquetted and as binders bentonite, water glass and cement were used. Briquettes made from dust from grinding with addition of water glass got compression strength after three months on the air about 82 kPa. Briquettes with addition of water glass were melted together with cast iron in electric induction furnace. Yield of metal from briquettes was around 80% and slag quantity around 4% (without briquettes the slag quantity was 1.4%).

PL

Pyły generowane w odlewni można podzielić na 3 grupy: pyły metaliczne zawierające ponad 70% Fe, pyły stanowiące mieszaninę Fe i SiO2 w ilości 10-70% oraz pyły o minimalnej zawartości SiO2 około 70%, będące odpadem. Pyły ze szlifowania zawierające około 88% żelaza na Słowacji wciąż są wywożone na składowisko. Celem pracy było opracowanie taniej metody aglomeracji tych pyłów, aby można je było przetapiać w piecu indukcyjnym. Pyły poddawano paletyzacji i brykietowaniu, a jako spoiwa stosowano szkło wodne, bentonit ora cement. W wyniku przeprowadzonych badan stwierdzono, że paletyzacja pyłów z proponowanymi spoiwami nie spełniła swojego zadania. Brykiety sporządzane z pyłów ze szlifowania odlewów z dodatkiem szkła wodnego uzyskiwały wytrzymałość na ściskanie rzędu 90 kPa, ale były bardzo kruche i nie nadawały się do transportu. Możliwe jest stosowanie dodatku brykietów do wsadu przy topieniu żeliwa w piecu indukcyjnym uzyskując stosunkowo wysoką wydajność (piec o pojemności 10 kg). Jednak należy przeprowadzić próby w piecu o większej pojemności.

5

Effect of melting technology on the properties of G17CrMo5-5 steel for cast turbines

Mańkowski P., Kalandyk B., Zapała R.

Archives of Foundry Engineering

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2010

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Vol. 10, iss. 4

133--136

EN

Two technologies of the G17CrMo 5-5 cast steel melting were compared, i.e. the so far used oxygen-recovery melting technology (electric arc furnace + ladle furnace – EAF + LF) and a new recovery melting technology (electric induction furnace + ladle furnace - EIF + LF). The effect of the melting technology on the properties of cast steel for turbine parts was determined. The cast steel was evaluated in term of its metallurgical purity and mechanical properties. During melting of G17CrMo 5-5 steel in induction furnace, lower total content of oxygen in casting was reached, but nitrogen content was higher than it was in the cast steel from arc furnace. Metal refining in LF improved the steel desulphurising degree and contributed to modification of the non-metallic inclusions.

6

Stała kontrola zużycia wymurówki i szczątkowej grubości ścianki w elektrycznych piecach do wytapiania, piecach podgrzewających i piecach odlewniczych/indywidualna kontrola jarzm w indukcyjnych piecach tyglowych

Maier K., Hopf M., Bachmann M.

Przegląd Odlewnictwa

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2009

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Vol. 59, nr 7-8

434-438

PL

Nie do końca dające się przewidzieć awarie oraz niszczenie wymurówki pieca przez metal prowadzą w odlewniach do wielu przestojów w produkcji, jak również stanowią szczególne zagrożenie dla personelu obsługującego piece. Coraz większego znaczenia nabierają techniki pomiaru pozwalające zapobiegawczo prowadzić naprawy zmierzające do wydłużenia żywotności pieców. Ważne staje się ustalanie terminów napraw, co pociąga za sobą eliminację lub ograniczenie przestojów. W artykule opisane zostały trzy systemy pomiaru oraz nadzoru pieców odlewniczych: SAVEWAY, SAVELINE oraz SAVESEARCH, które pozwalają na efektywne i bezpieczne wykorzystanie materiałów ogniotrwałych w urządzeniach do topienia, przetrzymywania i zalewania metalu. W zakresie indukcyjnych pieców tyglowych średniej częstotliwości artykuł koncentruje się na doświadczeniach praktycznych, dlatego też opisuje system selektywnej kontroli izolacji elektrycznej między cewką i każdym pojedynczym jarzmem w indukcyjnych piecach tyglowych.

EN

Unexpected failures and destroying of the furnace lining leads in foundries to several downtimes in the operation of induction furnaces; furthermore, they bring particular threat for the staff operating at these furnaces. So, greater and greater significance gather measuring techniques, allowing preventive repairs for increasing durability of the lining of such furnaces.. Very important becomes determining of the data of these repairs, thanks to what the dowbtimes can be eliminated or limited. In the article three measuring and controlling systems of the induction foundry furnaces, namely: SAVEWAY, SAVELINE and SAVESEARCH, have been described: they allow effectively and savely apply the refractories in the induction melting, holding and poring furnaces. In the scope of induction crucible furnaces of medium frequence the advantage was principally taken of practical experience, and that is why in the article the system of selective control of the electric insulation between the coil and each singular magnetic yoke in these furnaces has been described.